1. Field of the Invention
The present invention relates generally to the treatment of arterial disease, including for example, aortic occlusive disease, and in particular, to a universal modular stent graft assembly and method for treating arterial disease at the intersection of two or more arteries or blood flow passageways such as the intersection of the aorta and renal arteries or the aorta and posterior spinal arteries
2. Description of the Related Art
In the prior art, treatment of arterial disease was effected by various surgical techniques, some of which involved the use of stents and grafts. For example, it is well known in the art to interpose within the diseased portion of an artery a stent, whether made of stainless steel, nitinol or other materials capable of being balloon-expanded or self-expanded, for strengthening the walls of a stenotic or occluded artery. Grafts, comprised of hollow tubes of material such as Dacron, were normally inserted within the walls of a damaged artery and then sewn into position or expanded using a stented balloon catheter. It was also well known in the prior art to use a graft in conjunction with a stent to repair highly damaged portions of the aorta or other arteries thereby ensuring blood flow and reducing the risk of an aneurysm or rupture.
A more severe problem occurs when it is desirable to use a graft or a stented graft at or around the intersection of a major artery (e.g., the aorta) with intersecting collateral arteries (e.g., the renal arteries). While a stented graft could be used to strengthen and ensure the flow of blood through the aorta, the use of a stented graft could effectively seal or block off the blood flow to collateral organs, such as the kidneys. One technique for repairing weakened arterial walls is described in U.S. Pat. No. 5,617,878 to Taheri entitled “Stent and Method for Treatment of Aortic Occlusive Disease”, also referred to herein as Taheri 878. According to Taheri 878, the treatment included placing a graft at the intersection of two arteries. A cutting device was then used to make an opening in the graft at a point corresponding to the intersection of the two arteries. According to Taheri 878, a stent was then inserted into the graft and through the graft opening; the stent having a cylindrical collar with tines that grabbed and caught the walls of the graft to attach the stent to the opening in the graft whereby the flow of blood at the intersection of the arteries was allowed. The use of a “bifurcated” stent comprised of a single stent and graft adapted through cutting to incorporate a second stent and graft is described in U.S. Pat. No. 5,755,772 to Evans et al.
The Taheri 878 and Evans et al. prior art techniques discussed above, while somewhat effective, were cumbersome and difficult to employ and execute. Consequently, Taheri went on to create another method and structure set forth in U.S. Pat. No. 6,059,824 to Taheri entitled “Coupled Main and Collateral Stent and Method For Treatment Of Arterial Disease”, referred to herein as Taheri '824. According to Taheri '824, a stent assembly included first and second stents comprising a main graft and at least one intersecting collateral graft or, if desired, a main stented graft and at least one collateral stented graft for treating arterial disease at the intersection of various major arteries, e.g., the aorta and renal arteries or brachycephalic arteries. The method of Taheri '824 required first precisely measuring, through techniques such as ultrasound or other imaging, the exact location of the intersection of two arteries to be treated. To effectively use the method of Taheri '824, the size or diameter of the artery intersection point also needed to be precisely measured and the lateral opening of the main graft and the open end of the collateral graft had to be precisely sized so that once they were deployed and positioned in the respective main and collateral arteries, they would support the arteries at the point of intersection. According to Taheri '824, the main and collateral stented grafts were then coupled to each other with a system of detents and inlets, the detents of one being received in the inlets of the other to lock them together.
While Taheri '824 arguably provided some improvement over the Taheri 878 and Evans et al. prior art techniques discussed above, the method and structure of Taheri '824 shared significant drawbacks with Taheri 878 and Evans et al. For instance, as discussed above, Taheri '824 required a highly customized stented graft structure, that was “one of a kind”, having precisely measured and implemented features such as the longitudinal distance between branches, the radial positioning of the openings, and diameters of the openings. Consequently, the custom stented graft structures used with prior art techniques such as Taheri '824 were, of course, not subject to mass production and were very labor intensive and expensive to produce.
Another drawback to the custom stented graft structures used with prior art techniques was that it was not always possible to obtain the exact measurements required to build the custom stented graft structures used because, even with modern imaging technology, it is not always possible to see, and precisely measure, every location in the human body. To complicate matters further, even if the exact measurements were, in theory, available, there was significant opportunity for the introduction of error in both the measurement taking process and the implementation of those measurements in the production of the custom stented graft structure.
In addition, because the custom stented graft structures used with prior art techniques were custom made, there was considerable time lag between diagnosis and deployment of the stented graft structure while waiting for the custom stented graft structure to be built. In addition, since the stented graft structures used with prior art techniques were custom made, the delivery and deployment mechanisms were also variable and subject to error and unanticipated complications.
In short, custom stented graft structures used with the prior art required precise measurement and production techniques, were vulnerable to error, and had to be special ordered well in advance of their use. Consequently, the custom stented graft structures used with the prior art were far from ideal and had significant limitations.
What is needed is a method and apparatus for treating arterial disease that can be more flexibly applied and can be used on short notice in a variety of situations and on a variety of patients.